Titled ‘The Armstrong Lie,’ the movie will appear during the Toronto International Film Festival, which begins on September 5th and runs for eleven days.

The promo for the film gives a broad outline of what the documentary will deal with.

“Academy Award-winning director Alex Gibney (Taxi to the Dark Side) masterfully explores the fall of the disgraced cycling champion following the 2009 Tour de France, making use of his extraordinary access to attain rare interviews with former teammates, alleged doping mastermind Dr. Michele Ferrari, and Armstrong himself,” it states.

Gibney began filming Armstrong in 2009 when the Texan returned, and followed him for four years. His footage will include his preparation for the 2009 and 2010 Tours, the races themselves and also the fallout afterwards.

The documentary was originally anticipated to be a positive, somewhat feel-good movie, based on the initial indications from producer Frank Marshall. ‘In all of my sporting experience, I've never seen anything like it,” said an enthusiastic Marshall in 2009, speaking to the LA Times from the Tour de France. “We’re very pleased.”

He spoke glowingly of Armstrong, who was riding a wave of positive publicity generated by his comeback and the efforts of Livestrong plus his sponsors to promote his story, his return and his marketed message.

Gibney appears similarly enthralled. “What interested me was the story of his comeback -- his will,” he said then. “I wanted to understand Lance and what makes him tick. And the more I know, the more compelling the story gets.”

However, over time and with Armstrong’s downfall, the tone has changed completely. Since that publicity zenith of July 2009, his legend and reputation have been eroded by Floyd Landis’ allegations of drug use, the investigation into the Texan and his former teams, his increasingly implausible denials and his final admission in January of this year.

With that change Gibney’s own attitude – and the theme of the film – has also been modified. Ditto for Marshall, whose perception of Armstrong has been taken down a notch or two.

“We set out to make a movie about a comeback -- with unlimited and unprecedented access to Armstrong and the inner-workings of the Tour de France,” he said. “Along the way, we ended up chronicling the collapse of one of the greatest myths and legends of our time.”

Armstrong received a lifetime ban from USADA and his facing a number of legal suits, including a Qui Tam whistleblower case initiated by Landis and joined by the US Government. If deemed guilty of fraud, he and the other co-defendants could be liable for damages of tens of millions of dollars.

Armstrong has described his 2009 return as the biggest mistake of his career.